Lithium Battery Chemistries

Common types of lithium based batteries are in use currently and they include but not limited to:

  1. Lithium Ion (Li-ion)
  2. Lithium Polymer (Li-po)
  3. Lithium-thionyl chloride (Li-SOCl2)
  4. Lithium-sulfur dioxide (Li-SO2)
  5. Lithium-manganese dioxide (Li-MnO2)

Lithium Ion (Li-ion)

  • The lightest of all metals
  • The greatest electrochemical potential
  • The largest energy density for weight.
  • The load characteristics are reasonably good in terms of discharge.
  • The high cell voltage of 3.6 volts allows battery pack designs with only one cell versus three.
  • Is is a low maintenance battery.
  • No memory and no scheduled cycling is required to prolong the battery's life.
  • Lithium-ion cells
  • cause little harm when disposed.
  • It is fragile and requires a protection circuit to maintain safe operation.
  • Cell temperature is monitored to prevent temperature extremes.
  • Capacity deterioration is noticeable after one year (whether the battery is in use or not).

Lithium Polymer

  • The lithium-polymer differentiates itself from the conventional battery in the type of electrolyte used (a plastic-like film that does not conduct electricity but allows ion exchange – electrically charged atoms or groups of atoms).
  • The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte.
  • The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry.
  • Cell thickness measures as little as one millimeter (0.039 inches).
  • Can be formed and shaped in any way imagined.
  • Commercial lithium-polymer batteries are hybrid cells that contain gelled electrolyte to enhane conductivity.
  • Gelled electrolyte added to the lithium-ion-polymer replaces the porous separator. The gelled electrolyte is simply added to enhance ion conductivity.
  • Capacity is slightly less than that of the standard lithium-ion battery.
  • Lithium-ion-polymer finds its market niche in wafer-thin geometries, such as PDA batteries.
  • Improved safety – more resistant to overcharge; less chance for electrolyte leakage.

Lithium-manganese dioxide (Li-MnO2)

  • Lithium-manganese dioxide cells have a metallic lithium anode (the lightest of all the metals) and a solid manganese dioxide cathode.
  • Lithium-manganese dioxide cells are immersed in a non-corrosive, non-toxic organic electrolyte.
  • They deliver a voltage of 2.8 V and are cylindrical in shape, in 1/2 AA to D format, with spiral electrodes.

Lithium-sulfur dioxide (Li-SO2)

  • Lithium-sulphur dioxide cells have a metallic lithium anode (the lightest of all the metals) and a liquid cathode comprising a porous carbon current collector filled with a sulphur dioxide (SO2) solution.
  • They deliver a voltage of 2.8 V and are cylindrical in shape, in ½ AA to double-D format, with spiral electrodes.
  • Lithium-sulphur dioxide cells have a high energy density (250 Wh/kg) and a good capability for delivering repeated bursts of high power (up to 400 W/kg), derived from the spiral construction and is utilised in most of the applications addressed by this type of cell.

Lithium-thionyl chloride (Li-SOCl2)

  • Lithium-thionyl chloride cells have a metallic lithium anode (the lightest of all the metals) and a liquid cathode comprising a porous carbon current collector filled with thionyl chloride (SOCl2).

They deliver a voltage of 3.6 V and are cylindrical in shape, in 1/2AA to D format, with spiral electrodes for power applications and bobbin construction for prolonged discharge.

  • Lithium-thionyl chloride cells have a high energy density, partly because of their high nominal voltage of 3.6 V. Bobbin versions can reach 1220 Wh/L and 760 Wh/kg, for a capacity of 18.5 Ah at 3.6 V in D format. Because self-discharge is extremely low (less than 1% per year), this kind of cell can support long storage periods and achieve a service life of up to 20 years.
  • Until next time – Dan Hagopian, BatteryShip.com
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